So I just picked up a set of the Khantrol bipod adapters today and I've had two of the PASS adapters for a while so here's my take. Both sets pretty much do the same thing, one difference that I've noticed is that the Khantrol set uses a roll pin to attach the adapters to the bipod, much like how the stock Harris feet are attached. The PASS adapters attach via a small hex screw that threads into the body of the adapter itself. I can't say if one is more secure than the other one, I haven't installed the Kahntrol adapters yet. Fit and finish wise they're more or less the same and they both increase the height of the bipod by about an inch it's six of one half, a dozen of the other at this point. That being said, PASS has a Gen II adapter that is essentially quick disconnect so that you don't have to insert a bullet tip or something in order to release the feet, if I remember correctly you only have to push and rotate to get it to release, if it's important to you to be able to release the feet quickly to switch out accessories it could be the option for you.
